Machine parts used in the production of pig iron or steel, which in normal operation of a pig iron- or steel-producing plant come into contact with molten media such as pig iron, steel, slag, are covered by solidified deposits of these media. Such deposits alter the weight and dimensions of the machine parts. This results, inter alia, in the disadvantages that accurate shapes cannot be reliably ensured, machine parts can no longer be introduced or removed through openings dimensioned for the machine part without deposits or the drives which move the machine parts cannot cope with the additional weight of the deposits. To keep such disadvantages under control, it is usual to remove the deposits at regular intervals or replace machine parts coated with deposits. This requires a high outlay in terms of time and resources.